Some engines such as, for example, diesel engines, rely on compression ignition, where fuel is injected into a combustion chamber after air has been compressed to cause substantially immediate combustion without requiring a sparkplug. Compression ignition engines typically include a common rail fuel injection system, directing pressurized fuel to individual fuel injectors for injection into the combustion chamber. The fuel injector may include a needle check valve assembly reciprocatingly disposed within a cylindrical bore. To inject fuel, the needle check valve assembly may be selectively moved to open a nozzle outlet, thereby allowing high pressure fuel to spray from a nozzle supply passageway into the associated combustion chamber. The needle check valve assembly is typically secured within the fuel injector by a load screw.
A significant amount of torque may be applied to the load screw to adequately secure the valve assembly within the fuel injector. However, the clearances associated with the valve assembly may be extremely small, e.g., on the order of micrometers. The torque required to secure the valve assembly may be large enough to cause a misalignment of the valve assembly components, resulting in malfunction or damage to the valve assembly. A common industry practice is to use lubricants on the valve assembly to prevent misalignment during torquing, but these lubricants may mix with fuel during operation of the fuel injector, which may lead to improper engine operation.
One attempt at providing a valve assembly that addresses these shortcomings is described in U.S. Pat. No. 2,530,128 (the '128 patent) issued to Mashinter. The '128 patent discloses a fuel injector for supplying fuel to a cylinder of an internal combustion engine. Fuel is supplied from an external fuel source under pressure to a first reservoir within the fuel injector. The '128 patent discloses a ball and spring assembly to control the flow of fuel from the first reservoir to a second reservoir. The second reservoir has a valve assembly configured to provide fuel to a combustion chamber. The '128 patent discloses that a washer having a tab may help secure the spring within the fuel injector.
Although the fuel injector of the '128 patent may provide a method for providing fuel to a combustion chamber, it may fail to prevent and/or reduce misalignment of a fuel injector when a screw is tightened to secure a valve assembly within a fuel injector.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.